Human skin, as a primary protective barrier, protects the vital organs of the body from external irritants such as changes in temperature or humidity, ultraviolet rays and contaminants. However, as skin ages, the secretion of various hormones regulating metastasis is reduced, and the function of immunocytes and the activity of cells are lowered. In addition, due to the increase of UV light and oxygen free radicals resulting from contamination such as ozone layer destruction, physical and chemical stimulus and stress are generated, which promotes skin aging. In order to prevent skin aging and keep more healthy and beautiful skin, studies have been made to keep the inherent function of skin and to activate skin cells, and thereby to effectively inhibit skin aging, by using physiologically active substances obtained from various animals, plants and microorganisms.
It is known that EGCG increases the immunity of the human body, and has a superior antioxidant effect and anti-cancer effect when orally administered. In addition, it is known that, when applied on skin, EGCG promotes synthesis of collagen, which is the constituent of cartilage, capillary vessel and muscle, and destroys chemical substances generated by UV light, thereby preventing skin damage, as well as preventing skin aging, preserving healthy skin, and having superior whitening effects. Therefore, it is expected that EGCG shows excellent effects when applied in cosmetic composition as well as medical composition and home appliances.
However, as EGCG has a chemical structure of polyphenol, and has strong antioxidant effects, it reacts sensitively in external environments such as in air, especially to oxygen, heat and light, thereby being easily decomposed by oxidation.